Segmented structural links for coupled disk frequency tuning

ABSTRACT

A segmented structural link may comprise a base portion having a first face, a tail portion, and a distal end having a second face. The tail portion may extend at an angle relative to the first face. The tail portion may comprise a first bend and may further comprise a second bend. The base portion may comprise at least one of a captured nut, a nut plate, or a self-clinching nut.

FIELD

The disclosure relates generally to fans and fan hubs of gas turbine engines.

BACKGROUND

Gas turbine engines typically include a fan section to drive inflowing air, a compressor section to pressurize inflowing air, a combustor section to burn a fuel in the presence of the pressurized air, and a turbine section to extract energy from the resulting combustion gases. The fan section may include a plurality of fan blades coupled to a fan hub. The fan hub may experience vibrational modes in operation.

SUMMARY

In various embodiments the present disclosure provides a segmented structural link comprising a base portion having a first face, a tail portion, and a distal end having a second face. In various embodiments, the tail portion extends at an angle relative to the first face. In various embodiments, the tail portion comprises a first bend. In various embodiments, the tail portion further comprises a second bend. In various embodiments, the base portion further comprises at least one of a captured nut, a nut plate, or a self-clinching nut.

In various embodiments, the base portion is coupled at the first face to a first flange. In various embodiments, the distal end is coupled at the second face to a second flange. In various embodiments, the first flange is one of a J-flange or a scalloped flange. In various embodiments, the second flange is a forward flange of a hub comprising a cone arm coupled to a blade ring at a web. In various embodiments, the blade ring pivots over the cone arm about the web in response to a rotation of the hub. In various embodiments, the first flange is coupled to the blade ring and, in response to the blade ring pivoting over the cone arm about the web, is driven toward the second flange. In various embodiments, the segmented structural link is compressed in response to the first flange being driven toward the second flange.

In various embodiments the present disclosure provides a gas turbine engine comprising a fan section having a fan disk comprising a hub comprising a cone arm, a web, and a blade ring, a compressor section configured to compress a gas, a combustor section aft of the compressor section and configured to combust the gas, a turbine section aft of the combustor section configured to extract energy from the gas, and a segmented structural link wherein the segmented structural link comprises a base portion having a first face, a tail portion, and a distal end having a second face.

In various embodiments, the tail portion extends at an angle relative to the first face. In various embodiments, the tail portion comprises a first bend. In various embodiments, the base portion is coupled at the first face to a first flange and the distal end is coupled at the second face to a second flange. In various embodiments, a plurality of segmented structural links are distributed symmetrically about a circumference of the fan disk. In various embodiments, the segmented structural link extends around a portion of a circumference of the fan disk between a J-flange and a scalloped flange. In various embodiments, the segmented structural link is compressed in response to the first flange being driven toward the second flange.

In various embodiments, the present disclosure provides a method of tuning a vibrational response of a fan disk comprising calculating a vibrational mode shape of the fan disk, determining a point of maximum relative downward deflection of a blade ring of the fan disk, and coupling a segmented structural link to the fan disk at the point of maximum relative downward deflection between a first flange and a second flange.

The forgoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated herein otherwise. These features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosures, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements.

FIG. 1 illustrates an exemplary gas turbine engine, in accordance with various embodiments;

FIG. 2 illustrates a fan section having a segmented structural link, in accordance with various embodiments;

FIG. 3A illustrates a segmented structural link, in accordance with various embodiments;

FIG. 3B illustrates a segmented structural link, in accordance with various embodiments;

FIG. 4A illustrates a segmented structural link, in accordance with various embodiments;

FIG. 4B illustrates a segmented structural link, in accordance with various embodiments; and

FIG. 5 illustrates a method of tuning the vibrational response of a fan disk, in accordance with various embodiments.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration and their best mode. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosures, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the spirit and scope of the disclosures. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact.

In various embodiments and with reference to FIG. 1, a gas turbine engine 20 is provided. Gas turbine engine 20 may be a two-spool turbofan that generally incorporates a fan section 22, a compressor section 24, a combustor section 26 and a turbine section 28. Alternative engines may include, for example, an augmenter section among other systems or features. In operation, fan section 22 can drive air along a bypass flow-path B while compressor section 24 can drive air for compression and communication into combustor section 26 then expansion through turbine section 28. Although depicted as a turbofan gas turbine engine 20 herein, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures.

Gas turbine engine 20 may generally comprise a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine central longitudinal axis A-A′ relative to an engine static structure 36 via one or more bearing systems 38 (shown as bearing system 38-1 and bearing system 38-2). It should be understood that various bearing systems 38 at various locations may alternatively or additionally be provided, including for example, bearing system 38, bearing system 38-1, and bearing system 38-2.

Low speed spool 30 may generally comprise an inner shaft 40 that interconnects a fan 42, a low pressure (or first) compressor section 44 (also referred to a low pressure compressor) and a low pressure (or first) turbine section 46. Inner shaft 40 may be connected to fan 42 through a geared architecture 48 that can drive fan 42 at a lower speed than low speed spool 30. Geared architecture 48 may comprise a gear assembly 60 enclosed within a gear housing 62. Gear assembly 60 couples inner shaft 40 to a rotating fan structure. High speed spool 32 may comprise an outer shaft 50 that interconnects a high pressure compressor (“HPC”) 52 (e.g., a second compressor section) and high pressure (or second) turbine section 54. A combustor 56 may be located between HPC 52 and high pressure turbine 54. A mid-turbine frame 57 of engine static structure 36 may be located generally between high pressure turbine 54 and low pressure turbine 46. Mid-turbine frame 57 may support one or more bearing systems 38 in turbine section 28. Inner shaft 40 and outer shaft 50 may be concentric and rotate via bearing systems 38 about the engine central longitudinal axis A-A′, which is collinear with their longitudinal axes. As used herein, a “high pressure” compressor or turbine experiences a higher pressure than a corresponding “low pressure” compressor or turbine.

The core airflow C may be compressed by low pressure compressor 44 then HPC 52, mixed and burned with fuel in combustor 56, then expanded over high pressure turbine 54 and low pressure turbine 46. Mid-turbine frame 57 includes airfoils 59 which are in the core airflow path. Low pressure turbine 46, and high pressure turbine 54 rotationally drive the respective low speed spool 30 and high speed spool 32 in response to the expansion.

Gas turbine engine 20 may be, for example, a high-bypass geared aircraft engine. In various embodiments, the bypass ratio of gas turbine engine 20 may be greater than about six (6). In various embodiments, the bypass ratio of gas turbine engine 20 may be greater than ten (10). In various embodiments, geared architecture 48 may be an epicyclic gear train, such as a star gear system (sun gear in meshing engagement with a plurality of star gears supported by a carrier and in meshing engagement with a ring gear) or other gear system. Geared architecture 48 may have a gear reduction ratio of greater than about 2.3 and low pressure turbine 46 may have a pressure ratio that is greater than about 5. In various embodiments, the bypass ratio of gas turbine engine 20 is greater than about ten (10:1). In various embodiments, the diameter of fan 42 may be significantly larger than that of the low pressure compressor 44, and the low pressure turbine 46 may have a pressure ratio that is greater than about (5:1). Low pressure turbine 46 pressure ratio may be measured prior to inlet of low pressure turbine 46 as related to the pressure at the outlet of low pressure turbine 46 prior to an exhaust nozzle. It should be understood, however, that the above parameters are exemplary of various embodiments of a suitable geared architecture engine and that the present disclosure contemplates other gas turbine engines including direct drive turbofans.

In various embodiments, the next generation of turbofan engines may be designed for higher efficiency which is associated with higher pressure ratios and higher temperatures in the HPC 52. These higher operating temperatures and pressure ratios may create operating environments that may cause thermal loads that are higher than the thermal loads encountered in conventional turbofan engines, which may shorten the operational life of current components.

In various embodiments, HPC 52 may comprise alternating rows of rotating rotors and stationary stators. Stators may have a cantilevered configuration or a shrouded configuration. More specifically, a stator may comprise a stator vane, a casing support and a hub support. In this regard, a stator vane may be supported along an outer diameter by a casing support and along an inner diameter by a hub support. In contrast, a cantilevered stator may comprise a stator vane that is only retained and/or supported at the casing (e.g., along an outer diameter).

In various embodiments, rotors may be configured to compress and spin a fluid flow. Stators may be configured to receive and straighten the fluid flow. In operation, the fluid flow discharged from the trailing edge of stators may be straightened (e.g., the flow may be directed in a substantially parallel path to the centerline of the engine and/or HPC) to increase and/or improve the efficiency of the engine and, more specifically, to achieve enhanced compression and efficiency when the straightened air is compressed and spun by rotor 64.

According to various embodiments and with reference to FIGS. 1 and 2, a fan section 200 having a segmented structural link, is provided. Fan 202 comprises blade 206 coupled at blade root 207 to a fan disk 208 and compressor inlet cone 204. Fan 202 may be coupled to a shaft, such as inner shaft 40, where inner shaft 40 may be in mechanical communication with geared architecture 48. Tip 205 of blade 206 lies proximate rub strip 214 which forms a part of the inner aerodynamic surface 216 of fan case 210. A segmented structural link 302 lies radially inward of blade 206 aft of compressor inlet cone 204 at the forward face of fan disk 208. In various embodiments, a plurality of segmented structural links may be coupled circumferentially about the forward face of the disk. In various embodiments, segmented structural link 302 may be coupled proximate and radially outward of a shaft, such as inner shaft 40. Fan case 210 may be coupled at an aft end to pylon 218 which may be coupled to compressor case 220. As fan 202 rotates about the shaft it tends to draw in gas 222, such as, for example air, at the fore end of fan case 210. Rotating fan 202 tends to conduct gas 222 along inner aerodynamic surface 215 toward pylon 218 passing between inner aerodynamic surface 215 and compressor case 220 as fan exhaust 224.

In various embodiments and with reference to FIGS. 3A and 3B, a segmented structural link 302 is shown coupled to a fan disk 300. FIG. 3A illustrates fan disk 300 in a section through the x-y plane and FIG. 3B illustrates a perspective view of the fan disk 300 from the forward face looking aft. Segmented structural link 302 comprises a base portion 304 and a tail 306 extending at an angle θ relative to the plane of the forward face 305 of base portion 304. Tail 306 extends radially inward (along the x and y-axis) from the base portion toward a distal end 308 and may comprise one or more bends. In various embodiments, tail 306 may have a distal taper (along the y-axis) from base portion 304 toward distal end 308. Segmented structural link 302 is coupled at the base portion 304 to J-flange 312, with forward face 305 in contact with an aft face of J-flange 312. In various embodiments, base portion 304 further comprises a captured nut 321 and segmented structural link 302 that may be coupled at the base portion 304 via first fastener 310 extending through J-flange 312 and base portion 304 to engage captured nut 321. Distal end 308 is coupled at aft face 309 to forward flange 316 of hub 322.

In various embodiments, hub 322 engages a shaft, such as inner shaft 40, at splines 324 and in response to rotation of the shaft transmits torque from the shaft via cone arm 326 and web 328 to blade ring 330 causing blade ring 330 to rotate about the axis of the shaft. Blade ring 330 comprises channels 334 configured to receive a blade at a blade root, such as, for example, receiving blade 206 at blade root 207, and in this regard a fan, such as fan 202, may be caused to rotate about the shaft. In response to the rotation of the fan about the shaft, vibrations may be induced in the structure of the fan manifesting as a vibrational bending mode such as, for example, a first bending mode, a second bending mode, or a third bending mode. Blade ring 330 is coupled to J-flange 312 and, in response to a bending mode, tends to pivot over cone arm 326 about web 328 tending to induce a torque 332 which tends to cause a downward (relative to the y-axis) deflection of J-flange 312 which is in turn transmitted as a downward (relative to the y-axis) load “F” at J-flange 312. Stated another way, J-flange 312 is driven relatively towards forward flange 316 by downward load “F”. Downward load “F” is transmitted through segmented structural link 302 into forward flange 316 and is resisted by upward (relative to the y-axis) load “C” at forward flange 316 tending thereby to place segmented structural link 302 in compression. In this regard, segmented structural link 302 may be said to increase the stiffness of a fan disk, such as fan disk 208, by resisting vibrationally induced bending loads.

In various embodiments and with reference to FIGS. 4A and 4B, a segmented structural link 402 is shown coupled to a fan disk 400, which may comprise features, geometries, construction, manufacturing techniques, and/or internal components similar to fan disk 300 of FIGS. 3A and 3B. FIG. 4A illustrates fan disk 400 in a section through the x-y plane and FIG. 4B illustrates a perspective view of the fan disk 400 from the forward face looking aft. Segmented structural link 402 comprises a base portion 404 and tail portion 408 having a first bend 406 proximate base portion 404, a second bend 410 proximate a distal end 412, and extending at an angle θ relative to the plane of the aft face 434 of the base portion 404. Segmented structural link 402 extends in a continuous arc segment over a portion of the circumference of fan disk 400 and base portion 404 is coupled to J-flange 418 with aft face 434 of base portion 404 in contact with a forward face of J-flange 418 and coupled to scalloped flange 419 with aft face 434 of base portion 404 in contact with a forward face of scalloped flange 419. Distal end 412 is coupled at aft face 413 to forward flange 416 of hub 422. In response to a bending mode, blade ring 430 tends to pivot over cone arm 426 about web 428 tending to induce a torque 432 which tends to cause a downward (relative to the y-axis) deflection of J-flange 418 and scalloped flange 419 which is in turn transmitted as a downward (relative to the y-axis) load “F” at J-flange 312 and scalloped flange 419. Downward load “F” is transmitted through segmented structural link 402 into forward flange 416 and is resisted by upward (relative to the y-axis) load “C” at forward flange 416 tending thereby to place segmented structural link 402 in compression. In this regard, segmented structural link 402 may be said to increase the stiffness of a fan disk, such as fan disk 208, by resisting vibrationally induced bending loads.

In various embodiments, a blade ring, such as, for example, blade ring 330, may comprise one or more flanges or J-flanges, such as J-flange 312 or scalloped flange 313. In various embodiments, one or more segmented structural links such as, for example, segmented structural link 302 or segmented structural link 402, may be located circumferentially around the forward end of a fan disk, such as fan disk 300, and coupled between one or more flanges or J-flanges, such as J-flange 312 or scalloped flange 313, and a forward flange such as, for example forward flange 316 of a hub, such as hub 322, to resist vibrationally induced bending loads. In various embodiments, between one (1) and thirty-five (35) segmented structural links, or between five (5) and thirty (30) segmented structural links, or between ten (10) and twenty-five (25) segmented structural links may be distributed symmetrically about the circumference of a fan disk. In various embodiments, a segmented structural link, such as, for example segmented structural link 402, extends around a portion of the circumference of a fan disk, such as, for example, fan disk 400 between a J-flange and a scalloped flange or may extend around the entire circumference of a fan disk. In various embodiments, a fastener, such as fastener 314 or fastener 421, may comprise a threaded stud coupled to a forward flange, such as forward flange 316. In various embodiments, a captured nut, such as captured nut 321 or captured nut 420, may comprise a self-clinching nut, a nut plate, or any other captured fastener know to those skilled in the art. In various embodiments, a segmented structural link is one of a metal, an alloy, a steel, a titanium, a titanium alloy, a nickel, or a nickel alloy. In various embodiments angle θ is between zero degrees (0°) and sixty degrees (60°), or between ten degrees (10°) and fifty degrees (50°), or between twenty-five degrees (25°) and forty-five degrees (45°).

In various embodiments and with reference now to FIG. 5, a method 500 of tuning the vibrational response of a fan disk comprises calculating the vibrational mode shapes of a fan disk (502); determining a point of maximum relative downward deflection of a blade ring (504) of the fan disk; coupling a segmented structural link to the fan disk (506) at the point of maximum relative downward deflection between a first flange, such as, for example J-flange 312 of FIG. 3A, and a second flange, such as, for example, forward flange 316 of FIG. 3A.

Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosures.

The scope of the disclosures is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiment

Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element is intended to invoke 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. 

What is claimed is:
 1. A segmented structural link, comprising: a hub; a base portion having a first face; a tail portion; and a distal end having a second face.
 2. The segmented structural link of claim 1, wherein the tail portion extends at an angle relative to the first face.
 3. The segmented structural link of claim 2, wherein the tail portion comprises a first bend.
 4. The segmented structural link of claim 3, wherein the tail portion further comprises a second bend.
 5. The segmented structural link of claim 2, wherein the base portion further comprises at least one of a captured nut, a nut plate, or a self-clinching nut.
 6. The segmented structural link of claim 2, wherein the base portion is coupled at the first face to a first flange.
 7. The segmented structural link of claim 6, wherein the distal end is coupled at the second face to a second flange.
 8. The segmented structural link of claim 7, wherein the first flange is one of a J-flange or a scalloped flange.
 9. The segmented structural link of claim 8, wherein the second flange is a forward flange of the hub, wherein the hub further comprises a cone arm coupled to a blade ring at a web.
 10. The segmented structural link of claim 9, wherein the blade ring pivots over the cone arm about the web in response to a rotation of the hub.
 11. The segmented structural link of claim 10, wherein the first flange is coupled to the blade ring and, in response to the blade ring pivoting over the cone arm about the web, is driven toward the second flange.
 12. The segmented structural link of claim 11, wherein the segmented structural link is compressed in response to the first flange being driven toward the second flange.
 13. A gas turbine engine comprising: a fan section having a fan disk comprising a hub comprising a cone arm, a web, and a blade ring; a compressor section configured to compress a gas; a combustor section aft of the compressor section and configured to combust the gas; a turbine section aft of the combustor section configured to extract energy from the gas; and a segmented structural link wherein the segmented structural link comprises: a base portion having a first face; a tail portion; and a distal end having a second face.
 14. The gas turbine engine of claim 13, wherein the tail portion extends at an angle relative to the first face.
 15. The gas turbine engine of claim 14, wherein the tail portion comprises a first bend.
 16. The gas turbine engine of claim 15, wherein the base portion is coupled at the first face to a first flange and the distal end is coupled at the second face to a second flange.
 17. The gas turbine engine of claim 16, wherein a plurality of segmented structural links are distributed symmetrically about a circumference of the fan disk.
 18. The gas turbine engine of claim 16, wherein the segmented structural link extends around a portion of a circumference of the fan disk between a J-flange and a scalloped flange.
 19. The gas turbine engine of claim 16, wherein the segmented structural link is compressed in response to the first flange being driven toward the second flange.
 20. A method of tuning a vibrational response of a fan disk, the method comprising: calculating a vibrational mode shape of the fan disk; determining a point of maximum relative downward deflection of a blade ring of the fan disk; and coupling a segmented structural link to the fan disk at the point of maximum relative downward deflection between a first flange and a second flange. 